The invention relates generally to hook-lift hoists mounted on a wheeled chassis and, more specifically, to a hook-lift hoist that has a jib that is adjustable in length to accommodate containers for loading and transport by the hoist of two different heights.
Hook-lift hoists have been in common use, particularly in European countries, for a number of years. The hoist has a pivotable L-shaped arm with a hook on its distal end portion or jib that is used to engage a detachable truck box. The hook of the jib engages a loading bar of the container or truck box and the arm is pivoted to lift the container onto the chassis for transport of the container and its contents to any location.
The truck box containers are manufactured in a range of sizes, each having a characteristic size and rated weight capacity. In general, the larger the container, the larger its rated weight capacity and the higher from the ground its loading bar that is to be engaged by the hook on the jib of the hoist. In the past, hoists have generally been engineered to have a loading capacity matched to the maximum loaded weight of the container it can load and transport. Accordingly, the hook of a hoist had a preset height corresponding to the loading bar of the matching container.
It has become known also to provide the truck chassis with a lift mechanism for tilting of the box atop the chassis to dump the contents of the box rearwardly of the truck. Hook-lift hoists allow for a single truck chassis to be used with a wide variety of truck boxes, each of which has a distinct and advantageous use. A single truck chassis with a hook-lift hoist can be used, for example, to load, transport and dump open-topped waste receptacles to a disposal site; to load, transport, and unload shipping containers; to mount, use, and dismount road maintenance equipment, such as a salt spreader; to load, transport, and unload wheeled equipment; and so on. This functional versatility makes hook-lift hoists an economical vehicle for transport industries, particularly the street and highway maintenance departments of municipalities, states, and other governmental entities where budgetary constraints and the variety of tasks that must be performed make these multi-purpose vehicles an attractive choice.
Given the diversity of containers and other types of equipment that are to be loaded and transported on hook-lift hoists, it has become desirable to be able to load and transport containers and other equipment of more than one size onto a hook-lift hoist.